Security level is only configurable for 1st Gen functions, If
unspecified, SECURE_OPTIONAL will be used. 2nd Gen functions are
SECURE_ALWAYS ONLY.
Values:
SECURITY_LEVEL_UNSPECIFIED (0):
Unspecified.
SECURE_ALWAYS (1):
Requests for a URL that match this handler
that do not use HTTPS are automatically
redirected to the HTTPS URL with the same path.
Query parameters are reserved for the redirect.
SECURE_OPTIONAL (2):
Both HTTP and HTTPS requests with URLs that
match the handler succeed without redirects. The
application can examine the request to determine
which protocol was used and respond accordingly.
